Ray's New Intellectual Arithmetic · Lesson LXX · Unit 8: Percentage and interest
70. Commission
Goal: Your child works out an agent's commission and what the owner receives.
You'll need
- The book page (press “📖 Book page”, or use a printed copy)
- Paper for jotting, though the work is meant to be done in the head
What's in the book
A definition of commission, then eight problems on agents selling houses and grain.
The lesson, step by step
Warm up
Ask three or four problems from the last lesson again, out of order. Your child answers and says why.
Show the reasoning
SayAn agent sells a house for $4000 and charges 2½ per cent. 1 per cent of $4000 is $40, so 2½ per cent is $100.
Work the problems aloud
Read each problem on the page aloud. Your child answers, then explains in a full sentence, the way the book's model solutions do. The problems go like this:
An agent sells a $4000 house and charges 2½%: what is his commission?
A merchant sells 800 bushels of wheat at $1.25 and charges 2%: how much does the farmer get?
A merchant sells grain for $1000, charges 5% and buys $50 shares with the rest: how many shares?
Ask “Why?”
After each answer ask “Why?” or “How do you know?” Ray's wants the reasoning said aloud, not just the number. If your child stalls, go back to the model and say the first half of the explanation together.
Wrap up
Pick the two problems that were hardest today. Tomorrow, start with those as the warm-up.
Afterwards
Do the rest of the lesson's problems over the next day or two, a few at a time. Move on when your child can explain them without help.
Answers to the book's problems
1) $100. 2) $28. 3) $12.50. 4) $75; the owner gets $1425. 5) $980. 6) $2000. 7) $600. 8) 19 shares.
Worked out for this site from the scan. If a number in your copy differs, trust the book. Every answer is in Ray's own Key ↗.